Corrosion and wear resistant Fe-based alloys are used for the production of wear-susceptible pieces and parts of mechanical elements. Particularly, corrosion and wear resistant Fe-based alloys are widely used as liner materials in various industrial applications, including steel foundries, mines and quarries. Other applications of corrosion and wear resistant Fe-based alloys are seawater pumps, impellers, and drums for automotive vehicles.
At present, martensitic steel and high-chromium high-carbon steel having undergone annealing are exclusively used as corrosion and wear resistant materials.
Martensitic steel has relatively high corrosion resistance due to its low carbon content but suffers from poor wear resistance. In contrast, high-chromium high-carbon steel is highly wear resistant due to the formation of chromium carbides but suffers from poor corrosion resistance.
Under such circumstances, extensive research has been conducted to solve the disadvantages of the conventional corrosion and wear resistant Fe-based alloys. For example, methods have been developed in which expensive addition elements, e.g., molybdenum (Mo), tantalum (Ta), zirconium (Zr), tungsten (W), titanium (Ti), nickel (Ni) and copper (Cu), are blended and alloyed with iron (Fe) to prepare a high-hardness Fe-based alloy. Other methods have been developed in which a hard alloy, tungsten (W), a carbide or an oxide is adhered to a binder, e.g., iron (Fe) or nickel (Ni), as a base metal to prepare an Fe-based alloy.
An Fe-based alloy composed of iron (Fe) as a base metal and large amounts of alloying elements, e.g., molybdenum (Mo), zirconium (Zr) and tungsten (W), has improved corrosion and wear resistance but is disadvantageous in terms of preparation cost due to the use of the expensive addition elements. Further, an Fe-based alloy composed of a hard material and a high-toughness metal adhered to the hard material has improved corrosion and wear resistance but is difficult to prepare, thus inevitably causing an increase in preparation cost.
Thus, there is a need to develop a material that is prepared at low cost and is highly resistant to corrosion and wear.
Titanium alloys whose surface is covered (i.e. passivated) with an oxide film are highly resistant to corrosion when compared to other metal materials. Titanium alloys have attracted attention as biologically compatible materials because no damage resulting from stress corrosion cracking, which is a drawback of stainless steel, substantially occurs. For example, Ti-6Al-4V alloys are mainly used as biologically compatible materials for the fixation of bone fractures and biologically compatible prosthetic materials for artificial bones and artificial joints in orthopedic applications.
Since titanium is much more expensive (about 0.5-1 million Korean Won per kg) than iron (about 1,000 Korean Won per kg), the preparation of titanium alloys incurs a considerable cost. Nevertheless, high-priced titanium alloy scrap is wasted without being recycled after the production of biologically compatible materials due to the absence of its industrial use in Korea and is currently exported at a low price.
Thus, there is a need for an approach aimed at recycling titanium alloy scrap from the viewpoint of economical efficiency and environmental protection.